Long-term adverse influence of smoking during pregnancy on height and body size of offspring at ten years old in the UK Biobank cohort

Abstract Background To explore the long-term relation between smoking during pregnancy and early childhood growth in the UK Biobank cohort. Methods To estimate the effect of smoking during pregnancy on offspring height and body size at ten years old, we performed a cross-population comparison to examine whether such influence could be repeatedly observed among three different ethnic groups in the UK Biobank cohort (n = 22,140 for European, n = 7,094 for South Asian, and n = 5,000 for African). Especially, we applied the UK Biobank European sibling cohort (n = 9,953 for height and n = 7,239 for body size) to control for unmeasured familial confounders and incorporated a polygenic risk score to adjust for potential genetic effect. Results We discovered that children whose mothers smoked during pregnancy had greater risk of being shorter or fatter at age ten in the full UK Biobank European cohort, with 15.3% (95% confidence intervals (CIs): 13.0 ~ 17.7%) higher risk for height and 32.4% (95%CIs: 29.5 ~ 35.4%) larger risk for body size. Similar associations were identified in the South Asian and African populations. These associations were robust and remained significant in the European sibling cohort (12.6% [95%CIs: 5.0 ~ 20.3%] for height and 36.1% [95%CIs: 26.3 ~ 45.9%] for body size) after controlling for family factors or genetic influence. Conclusion Smoking during pregnancy can promote offspring's height defect and obesity in childhood.